NEW YORK (Reuters Health) - Children age 10 and younger are
more likely than older kids and adults to be sickened by
swimming in bacteria-contaminated water, researchers from the
Environmental Protection Agency (EPA) and the Centers for
Disease Control and Prevention report.

Experts had long suggested that children might be at
greater risk of swimming-related illness than adults, Dr.
Timothy J. Wade of the EPA's National Health and Environmental
Effects Research Laboratory in Chapel Hill, North Carolina, and
colleagues note, but this is the first research to show that
this is actually the case.

Wade and his team also found that an experimental method
for gauging water quality by checking for bacterial DNA was not
only quicker than the standard technique, but better able to
predict pollution-associated health risks.

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"Overall the current guidelines are protecting public
health, but this probably has the potential to do better," Wade
told Reuters Health. "Results can be obtained much faster and
therefore an action could be taken much faster."

He and his colleagues compared water contamination levels
and illness risk among visitors to three beaches on Lake
Michigan and one on Lake Erie in 2003 and 2004.

Currently, local authorities will typically test beach
water quality by trying to grow certain types of bacteria from
water samples, which can take 24 to 48 hours to yield results.
The newer method called quantitative polymerase chain reaction
(QPCR) may be able to reveal contamination levels in as little
as two hours.

To determine how well testing methods were able to gauge
illness risk, the researchers tested water quality. Ten to 12
days later they interviewed people who had been visiting the
beach on that day to see if anyone had gotten sick. Their
analysis covered 78 days and included 1,359 water samples and
21,105 interviews.

On about one-third of the days, levels of Enterococcus
bacteria in the water exceeded recommended levels as measured
by standard tests, the investigators found.

The risk of reporting gastrointestinal illness after a
beach visit rose as the amount of Enterococcus in the water,
measured by QPCR, increased, the researchers found, and the
increased risk was greater among children 10 years old and
younger.

Enterococcus levels as measured by QPCR were a more
accurate predictor of illness risk than the standard testing
method.

"In terms of the overall ability to predict health effects,
the new method was better," Wade said. Some localities are
experimenting on their own with QPCR for testing water quality,
he added, although the older method remains the standard for
public health advisories.